This invention relates to analog amplifiers and digital controllers having analog input operating parameters, and, more particularly, to an operational amplifier that is configurable as a programmable gain amplifier or a general purpose amplifier, and to a single monolithic device such as an integrated circuit die or multi-chip package comprising a microcontroller and/or a digital signal processor (DSP) in combination with at least one analog operational amplifier that is configurable as a programmable gain amplifier or a general purpose amplifier.
Analog amplifiers and digital controllers are becoming more sophisticated while continuing to drop in price. More and more consumer and commercial products, such as for example but not limited to, appliances, telecommunications devices, automobiles, security systems, full-house instant hot water heaters, lighting control, thermostats, humidistats, sprinkler control systems and the like are being operated by these digital controllers.
Analog inputs for receiving sensor information are necessary for the application of these controllers. Heretofore separate and discrete analog interfaces were used to connect a digital controller to the outside world. Digital controllers were created from programmable logic arrays (PLA), field or mask programmable gate arrays (FPGA or PGA), microcontrollers or digital signal processors (DSP) in combination with software or firmware programs.
Analog input devices such as analog-to-digital converters (ADC) in conjunction with a separate operational amplifier were used to convert a time-varying analog signal into digital representations thereof for application to digital inputs of the digital controller and use thereof. Voltage and current levels were also detected by discrete integrated circuit voltage comparators that changed a digital output state when a certain analog value was present on the input of the comparator. Analog control outputs were generated by digital-to-analog converters (DAC) in combination with the digital controller.
Technology has now advanced to the point where the analog input and output devices can be fabricated on the same integrated circuit die or multi-chip package (MCP) as the digital controller, thus producing mixed signal integrated circuits. Mixed signal integrated circuits reduce the cost, size and power consumption of controller systems. There are a large number of different applications and requirements for control systems, therefore an integrated circuit controller must have a great deal of flexibility and capability for use in various systems configurations. To be cost effective, the integrated circuit controller should be mass-produced as a single monolithic device. Analog input peripheral devices of the integrated circuit controller must interface with analog signals that may have a wide range of voltage and/or current levels. Since there are so many different types of analog signals, many different types of analog amplifiers (operational amplifiers are required because it is difficult to add programmable gain amplifier (PGA) to a general purpose operational amplifier (Op Amp) without affecting the performance of the Op Amp. Increasing the flexibility of an analog amplifier also increases its design complexity.
What is needed is an analog amplifier, and/or a digital controller having an analog amplifier(s) that may be configured as a PGA or a general purpose operational amplifier without operational degradation or increased circuit complexity of the analog amplifier.
The invention overcomes the above-identified problems as well as other shortcomings and deficiencies of existing technologies by providing an analog amplifier that may be configured as a PGA or a general purpose Op Amp, or an analog amplifier that may be configured as a PGA or a general purpose Op Amp and a digital controller fabricated as a single monolithic device such as an integrated circuit semiconductor die or a multi-chip package (MCP). An Op Amp in combination with digital logic controlled analog switches and gain setting resistors allows the Op Amp to be configured as a PGA or a general purpose Op Amp. The analog switches may be controlled by a processor (microcontroller, PLA, ASIC, DSP and the like) which may be fabricated on a different or the same integrated circuit die or in the MCP.
In accordance with an exemplary embodiment, the present invention is directed to a system for a processor and configurable amplifier system, said system comprising: a processor; an amplifier having an input and an output; a first switch having a plurality of inputs and an output; a second switch having an input and an output; said first and second switches controlled by said processor; a plurality of gain determining elements connected to the inputs of said first and second switches; said second switch output coupled to the output of said amplifier; and said first switch output coupled to the input of said amplifier; wherein said amplifier is configured as a general purpose amplifier without gain determining elements connected thereto when said first switch selects a first one of the plurality of inputs and said second switch is off, and said amplifier is configured as a programmable gain amplifier when said first switch selects any other one of the plurality of inputs and said second switch is on, whereby said gain determining elements determine the gain of said amplifier.
The present invention is also directed to a method of operation for configuring an operational amplifier as either a programmable gain amplifier or a general purpose amplifier, said method comprising the steps of: providing a processor; providing an amplifier having an input and an output; providing a first switch having a plurality of inputs and an output; providing a second switch having an input and an output; controlling said first and second switches with said processor; providing a plurality of gain determining elements connected to the inputs of said first and second switches; coupling said second switch output to the output of said amplifier; coupling said first switch output to the input of said amplifier; configuring said amplifier as a general purpose amplifier without gain determining elements connected thereto when said first switch selects a first one of the plurality of inputs and said second switch is off; and configuring said amplifier as a programmable gain amplifier when said first switch selects any other one of the plurality of inputs and said second switch is on, whereby said gain determining elements determine the gain of said amplifier.
The present invention is also directed to an apparatus for a configurable amplifier, said configurable amplifier comprising: an amplifier having an input and an output; a first switch having a plurality of inputs and an output; a second switch having an input and an output; said first and second switches are adapted for digital control; a plurality of gain determining elements connected to the inputs of said first and second switches; said second switch output coupled to the output of said amplifier; and said first switch output coupled to the input of said amplifier; wherein said amplifier is configured as a general purpose amplifier without gain determining elements connected thereto when said first switch selects a first one of the plurality of inputs and said second switch is off, and said amplifier is configured as a programmable gain amplifier when said first switch selects any other one of the plurality of inputs and said second switch is on, whereby said gain determining elements determine the gain of said amplifier.
A feature of the present invention is an analog programmable gain amplifier or a standard operational amplifier that may be configured using external gain setting components.
Still another feature is configuration of an analog programmable gain amplifier or a standard operational amplifier with a digital processor.
Another feature is access to the inputs and outputs of the analog amplifier to connect feedback components thereto.
Another feature is programmable access to the inputs and outputs of the analog amplifier to connect feedback components thereto.
Other and further features and advantages will be apparent from the following description of exemplary embodiments of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawings.